Neural-dural transition at the medial anterior cranial base: an anatomical and histological study with clinical applications.

OBJECT: Few anatomical studies have been focused on the morphological features and microscopic anatomy of the transition from the intracranial space to the medial anterior cranial base. The authors of the current study performed histological analyses to define the structure of the transition from neural foramina to the cranial base (neural-dural transition) at the cribriform plate, particularly as related to cerebrospinal fluid (CSF) fistula formation and surgical intervention in the region.
METHODS: The medial anterior cranial base was resected in six cadaveric specimens. Histological methods were used to study the anatomy of the region on the microscopic level. Results of these examinations revealed a multilayered neural-dural transition at the cribriform plate, which consisted of an arachnoid membrane and a potential subarachnoid space as well as dura mater, periosteum, ethmoid bone, and associated layers of submucosa and mucosa of the paranasal air spaces. A subarachnoid space was identified around the olfactory nerves as they exited the neural foramina of the cribriform plates. The dura mater eventually thinned out and became continuous with the periosteum in the ethmoid bone. The dura, arachnoid membrane, and associated potential subarachnoid space were obliterated at a place 1 to 2 mm into the olfactory foramen. The authors present a case of recurrent CSF rhinorrhea successfully treated using a technique of multilayered reconstruction with pericranium, fat, and bone.
CONCLUSIONS: The findings provide an anatomical basis for CSF fistula formation in the region of the cribriform plate and help to explain the unusual presentations in patients who have CSF rhinorrhea and meningitis. These results may facilitate the treatment of CSF fistulas, repair of defects in the medial anterior cranial base, and approaches to tumors and other pathological entities in the region.